System and method of controlling fluid to a fluid consuming battery

ABSTRACT

A fluid regulating system is provided for controlling fluid to a fluid consuming battery having a fluid consuming cell. The fluid regulating system includes a valve having a moving plate disposed adjacent to a fixed plate, and both having fluid entry ports to open and close a valve. The fluid regulating system also includes an actuator for moving the moving plate to open and close the valve. The actuator is controlled to open the valve when greater battery electrical output is required to operate a device and maintains the valve in the open position for a minimum required time to minimize battery capacity loss due to operation of the fluid regulating system.

BACKGROUND OF THE INVENTION

This invention generally relates to fluid regulating systems forcontrolling the rate of entry of fluids, such as gases, into and out ofelectrochemical batteries and cells with fluid consuming electrodes, andto the batteries and cells in which such fluid regulating systems areused, particularly air-depolarized, air-assisted and fuel cells andbatteries.

Electrochemical battery cells that use a fluid, such as oxygen and othergases, from outside the cell as an active material to produce electricalenergy, such as air-depolarized, air-assisted and fuel cell batterycells, can be used to power a variety of portable electronic devices.For example, air enters into an air-depolarized or air-assisted cell,where it can be used as, or can recharge, the positive electrode activematerial. The oxygen reduction electrode promotes the reaction of theoxygen with the cell electrolyte and, ultimately, the oxidation of thenegative electrode active material with the oxygen. The material in theoxygen reduction electrode that promotes the reaction of oxygen with theelectrolyte is often referred to as a catalyst. However, some materialsused in oxygen reduction electrodes are not true catalysts because theycan be at least partially reduced, particularly during periods ofrelatively high rate of discharge.

One type of air-depolarized cell is a zinc/air cell. This type of celluses zinc as the negative electrode active material and has an aqueousalkaline (e.g., KOH) electrolyte. Manganese oxides that can be used inzinc/air cell air electrodes are capable of electrochemical reduction inconcert with oxidation of the negative electrode active material,particularly when the rate of diffusion of oxygen into the air electrodeis insufficient. These manganese oxides can then be reoxidized by theoxygen during periods of lower rate discharge or rest.

Air-assisted cells are hybrid cells that contain consumable positive andnegative electrode active materials as well as an oxygen reductionelectrode. The positive electrode can sustain a high discharge rate fora significant period of time, but through the oxygen reductionelectrode, oxygen can partially recharge the positive electrode duringperiods of lower or no discharge, so oxygen can be used for asubstantial portion of the total cell discharge capacity. This means theamount of positive electrode active material put into the cell can bereduced and the amount of negative electrode active material can beincreased to increase the total cell capacity. Examples of air-assistedcells are disclosed in commonly assigned U.S. Pat. Nos. 6,383,674 and5,079,106.

An advantage of air-depolarized, air-assisted, and fuel cells is theirhigh energy density, since at least a portion of the active material ofat least one of the electrodes comes from or is regenerated by a fluid(e.g., a gas) from outside the cell.

A disadvantage of these cells is that the maximum discharge rates theyare capable of can be limited by the rate at which oxygen can enter theoxygen reduction electrode. In the past, efforts have been made toincrease the rate of oxygen entry into the oxygen reduction electrodeand/or control the rate of entry of undesirable gases, such as carbondioxide, that can cause wasteful reactions, as well as the rate of waterentry or loss (depending on the relative water vapor partial pressuresoutside and inside the cell) that can fill void space in the cellintended to accommodate the increased volume of discharge reactionproducts or dry the cell out, respectively. Examples of these approachescan be found in U.S. Pat. No. 6,558,828; U.S. Pat. No. 6,492,046; U.S.Pat. No. 5,795,667; U.S. Pat. No. 5,733,676; U.S. Patent Publication No.2002/0150814; and International Patent Publication No. WO02/35641.However, changing the diffusion rate of one of these gases generallyaffects the others as well. Even when efforts have been made to balancethe need for a high rate of oxygen diffusion and low rates of CO₂ andwater diffusion, there has been only limited success.

At higher discharge rates, it is more important to get sufficient oxygeninto the oxygen reduction electrode, but during periods of lowerdischarge rates and periods of time when the cell is not in use, theimportance of minimizing CO₂ and water diffusion increases. To providean increase in air flow into the cell only during periods of high ratedischarge, fans have been used to force air into cells (e.g., U.S. Pat.No. 6,500,575), but fans and controls for them can add cost andcomplexity to manufacturing, and fans, even micro fans, can take upvaluable volume within individual cells, multiple cell battery packs anddevices.

Another approach that has been proposed is to use valves to control theamount of air entering the cells (e.g., U.S. Pat. No. 6,641,947 and U.S.Patent Publication No. 2003/0186099), but external means, such as fansand/or relatively complicated electronics, can be required to operatethe valves.

Yet another approach has been to use a water impermeable membranebetween an oxygen reduction electrode and the outside environment havingflaps that can open and close as a result of a differential in airpressure, e.g., resulting from a consumption of oxygen when the batteryis discharging (e.g., U.S. Patent Publication No. 2003/0049508).However, the pressure differential may be small and can be affected bythe atmospheric conditions outside the battery.

Commonly assigned U.S. Patent Publication No. 2005/0136321 discloses avalve that is operated by an actuator that responds to changes in apotential applied across the actuator to open and close the valve.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a method ofcontrolling fluid supplied to a fluid consuming battery is provided. Themethod includes the step of providing a fluid regulating system thatcomprises a valve for adjusting rate of passage of fluid into a fluidconsuming electrode of a battery and an actuator for operating thevalve. The method also includes the steps of sensing an operatingcondition of the fluid regulating system, and determining a minimumrequired time for maintaining the valve in the open position based onthe sensed operating condition. The method further includes the steps ofcontrolling actuation of the valve to open the valve when greaterbattery electrical output is required, maintaining the valve in the openposition for the minimum required time, and controlling actuation of thevalve to close the valve when lesser battery electrical output isrequired.

According to another aspect of the present invention, a fluid regulatingsystem is provided for regulating fluid to a fluid consuming battery.The system includes a valve for adjusting rate of passage of fluid intoa fluid consuming electrode of a battery, and an actuator for operatingthe valve between at least an open position and a closed position. Thesystem also includes a sensor for sensing an operating condition of thefluid regulating system. The system further includes a controller forcontrolling operation of the actuator to open and close the valve. Thecontroller controls the actuator to open the valve when greater batteryelectrical output is required and to close the valve when lesser batteryelectrical output is required. The controller maintains the valve in theopen position for a minimum required time period. The minimum requiredtime period is determined based on the sensed operating condition.

These and other features, advantages, and objects of the presentinvention will be further understood and appreciated by those skilled inthe art by reference to the following specification, claims, andappended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective view of a battery constructed in accordance witha first embodiment of the present invention showing the top of thebattery;

FIG. 2 is a perspective view of the battery shown in FIG. 1 showing thebottom of the battery;

FIG. 3 is an exploded perspective view showing the bottom of the batteryalong with the components forming a fluid regulating system used withthe battery;

FIG. 4 is a perspective view of the first construction of a fluidregulating system useful in the battery shown in FIGS. 1 and 16;

FIGS. 5A and 5B are partial cross-sectional views illustrating the valveof the fluid regulating system in open and closed positions;

FIG. 6 is a top view of a fluid regulating system employing anotheractuator construction and an overmolded chassis useful with the presentinvention;

FIG. 7 is a top view of a fluid regulating system employing an actuatorwith a single pin, according to another embodiment;

FIG. 8 is a top view of a fluid regulating system employing an alternatepin actuator assembly;

FIGS. 9A and 9B are cross-sectional views of the portion of the batteryincluding the valve as used in one embodiment of the present invention;

FIG. 10 is an alternative construction of a fluid regulating system thatmay be used in the various embodiments of the present invention;

FIG. 11 is an exploded perspective view of a variation of the battery ofthe first embodiment of the present invention;

FIG. 12 is a partial cross-sectional view of one possible implementationof the alternative battery construction shown in FIG. 11;

FIG. 13 is another possible configuration of the alternative batteryconstruction shown in FIG. 11;

FIG. 14 is a partial cross-sectional view showing a different batteryconstruction for the first embodiment;

FIG. 15 is a partial cross-sectional view of yet another possibleimplementation of the battery according to the first embodiment;

FIG. 16 is an exploded perspective view of a second embodiment of abattery constructed in accordance with the present invention;

FIG. 17 is a partial cross-sectional view of the battery shown in FIG.16;

FIG. 18 is a cross-sectional view showing the details of an electricalcontact tab that may be used with either the first or second embodimentof the present invention;

FIG. 19 is a partial cross-sectional view showing an alternativeconstruction of a battery according to the second embodiment of thepresent invention;

FIG. 20 is a partial perspective view of a modified can that may be usedin the construction shown in FIG. 19;

FIG. 21 is a partial perspective view of a gasket that may be used inthe construction shown in FIG. 19;

FIG. 22 is a cross-sectional view of a portion of the gasket shown inFIG. 21;

FIG. 23 is an exploded perspective view of a battery in accordance witha third embodiment of the invention, with the fluid regulating systemactuators and control circuit not shown;

FIG. 24 is a cross-sectional view of the fluid regulating system of thebattery shown in FIG. 23, as viewed from the right side;

FIG. 25 is a cross-sectional view of a fluid regulating system inaccordance with a fourth embodiment of the invention;

FIG. 26 is an exploded partial perspective view of a portion of a fluidregulating system in accordance with an embodiment of the invention;

FIG. 27A is a top view of an embodiment of a valve in a closed positionand including a schematic diagram of a portion of a control circuit;

FIG. 27B is a top view of an embodiment of the valve shown in FIG. 27A,but with the valve in an open position;

FIG. 27C is a top view of an embodiment of the valve shown in FIG. 27B,but with an actuator in an elongated condition;

FIG. 27D is a top view of an embodiment of the valve shown in FIG. 27A,but with both actuators in a shortened condition;

FIG. 28 is a perspective of an SMA wire fastened to a connector;

FIG. 29 is a top view of a fluid regulating system employing a passiveclosure actuator, according to one embodiment;

FIG. 30 is a perspective view of a battery having a fluid regulatingsystem with a pressure equalization fluid passage provided in thechassis, according to another embodiment;

FIG. 31 is an exploded perspective view of the battery having a fluidregulating system with a fluid passage shown in FIG. 30;

FIG. 32 is a cross-sectional view of a portion of the battery and fluidregulating system taken through lines XXXII-XXXII of FIG. 30;

FIG. 33 is a cross-sectional view of the chassis taken through linesXXXIII-XXXIII of FIG. 31 further illustrating baffles forming a tortuousfluid passage;

FIG. 34 is an exploded perspective view of a battery having a fluidregulating system with a pressure equalization fluid passage, accordingto another embodiment;

FIG. 35 is an exploded perspective view of a battery having a fluidregulating system employing a chassis and an electrically conductiveframe encapsulated in the chassis, according to one embodiment;

FIG. 36 is a perspective view of an electrically conductive frameemployed in the fluid regulating system of FIG. 35;

FIG. 37 is a perspective view of the electrically conductive framehaving electrical components including position sensors assembledthereon;

FIG. 38 is a perspective view of the electrically conductive framesubstantially encapsulated within a chassis;

FIG. 39 is a perspective view of the chassis and frame following removalof excess frame elements;

FIG. 40 is a perspective view of the fluid regulating system followingassembly of the actuator, according to one embodiment;

FIG. 41 is an enlarged view of section XLI of FIG. 40, furtherillustrating the press fit assembly of the actuator crimp in the crimpopening and a position sensor;

FIG. 42 is a cross-sectional view taken through lines XLII-XLII in FIG.41, further illustrating the press fit assembly;

FIG. 43 is a cross-sectional view of a crimp connection prior toassembly according to another embodiment;

FIG. 44 is a cross-sectional view of the assembled crimp connectionshown in FIG. 43;

FIG. 45 is a cross-sectional view of a crimp connection prior toassembly according to a further embodiment;

FIG. 46 is a cross-sectional view of the assembled crimp connectionshown in FIG. 45;

FIG. 47 is a perspective view of the battery following assembly of thefluid consuming cell to the chassis;

FIG. 48 is a perspective view of the battery illustrating connection ofthe battery contacts from the frame to the battery terminals;

FIG. 49 is a perspective view of the completely assembled battery;

FIG. 50 is a top plan view of a fluid regulating system illustrating twoposition sensors embedded in the chassis, according to one embodiment ofthe present invention;

FIG. 51 is a block diagram illustrating control circuitry forcontrolling the valve of the fluid regulating system according to oneembodiment of the present invention;

FIG. 52 is a state diagram illustrating the state logic executed by thecontrol circuitry to control the valve, according to one embodiment ofthe present invention; and

FIG. 53 is a lookup table illustrating minimum required times formaintaining the valve in the open position based on a sensedtemperature, according to one embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of this invention include a fluid regulating system for abattery that includes an electrochemical cell that utilizes a fluid(such as oxygen or another gas) from outside the cell as an activematerial for one of the electrodes. The cell has a fluid consumingelectrode, such as an oxygen reduction electrode. The cell can be anair-depolarized cell, an air-assisted cell, or a fuel cell. The batteryemploys the fluid regulating system for adjusting the rate of passage offluid to the fluid consuming electrode (e.g., the air electrodes inair-depolarized and air-assisted cells) to provide a sufficient amountof the fluid from outside the cell for discharge of the cell at highrate or high power, while minimizing entry of fluids into the fluidconsuming electrode and water gain or loss into or from the cell duringperiods of low rate or no discharge.

Preferably the fluid regulating system will have a fast response tochanges in cell potential, a long cycle lifetime, a low operatingvoltage that is well matched to the cell voltage range on discharge, anda high efficiency. In addition, the regulating system will preferablyhave a low permeability to the fluids being managed in the closedposition, open and close in proportion to the need for the active fluidin the cell, require only a very small amount of the total celldischarge capacity, have a small volume and be easy and inexpensive tomanufacture and incorporate into or onto the cell, battery or device.

As used herein, unless otherwise indicated, the term “fluid” refers tofluid that can be consumed by the fluid consuming electrode of a fluidconsuming cell in the production of electrical energy by the cell. Thepresent invention is exemplified below by air-depolarized cells withoxygen reduction electrodes, but the invention can more generally beused in fluid consuming cells having other types of fluid consumingelectrodes, such as fuel cells. Fuel cells can use a variety of gasesfrom outside the cell housing as the active material of one or both ofthe cell electrodes.

As described further below with respect to FIGS. 1-3, a battery 10 isshown including a fluid consuming cell 20 and a fluid regulating system50. The fluid regulating system 50 regulates the flow of fluid to thefluid consuming electrode(s) of fluid consuming cell 20. For anair-depolarized cell, the fluid regulating system is disposed inside oroutside of a cell housing 30 of fluid consuming cell 20 and on the airside of the oxygen reduction electrode (i.e., the side of the oxygenreduction electrode that is accessible to air from the outside of thecell housing).

A first embodiment of a battery 10 is shown in FIGS. 1-3. As shown,fluid consuming cell 20 (in this case an air-depolarized cell) includesa cell housing 30, which includes a first housing component and a secondhousing component, which may include a can 34 and a cover 36,respectively, or may have shapes or sizes differing from what wouldotherwise be considered a can or cover. For purposes of example, thefirst housing component is hereinafter referred to as can 34, while thesecond housing component is hereinafter referred to as cover 36. Can 34and cover 36 are both made of an electrically conductive material, butare electrically insulated from one another by means of a gasket 38(FIG. 12). Can 34 generally serves as the external positive contactterminal for the fluid consuming cell 20, whereas cover 36 serves as theexternal negative contact terminal. As discussed further below, cell 20further includes a first electrode 40, which may be the fluid consumingelectrode or air electrode, a second electrode 42, which may be thenegative electrode (i.e., anode), and a separator 44 disposed betweenthe first and second electrodes (see FIG. 12). First electrode 40 ispreferably electrically coupled to can 34, whereas second electrode 42is preferably electrically coupled to cover 36.

Can 34 includes a bottom surface 35 in which a plurality of fluid entryports 32 are provided such that fluid may pass to the interior of cellhousing 30 so as to reach the fluid consuming electrode 40 (see FIG.12).

In the embodiment shown in FIGS. 1-3, the fluid regulating system 50 issecured to the exterior of bottom surface 35 of can 34. The particularmanner by which fluid regulating system 50 may be attached to theexterior of cell 20 is discussed further below. In addition, furtherembodiments are described below in which fluid regulating system 50 isincorporated on the inside of fluid consuming cell 20.

The fluid regulating system 50 according to this particular embodimentmay include a valve 60 including a first plate 62 (which may correspondto bottom surface 35 of can 34) having a plurality of apertures 64(which may correspond to fluid entry ports 32), and a movable secondplate 66 including a plurality of apertures 68 that correspond in size,shape, number, and position to apertures 64 formed in first plate 62.The size, shape, number, and position of apertures 64 and 68 arepreferably optimized to provide the desired volume and distribution offluid applied to the fluid consuming electrode. The size, shape, numberand relative location of apertures 64 do not have to be the same as thesize, shape, number and relative location of apertures 68. For example,if apertures 64 are slightly different in size from apertures 68,precise alignment of apertures 64 and 68 is not essential to achieve themaximum total open area through plates 62 and 66.

Fluid regulating system 50 may further include a chassis 70 having anannular body portion 72 with an opening 74 in which second plate 66 isdisposed. Opening 74 is preferably shaped and sized to contact theelongated side edges of plate 66 while providing excess space at theshorter side of plate 66 such that plate 66 may be slid linearly alongan axis in parallel with its longest dimension. Thus, as shown in FIGS.5A and 5B, the apertures 68 of second plate 66 may be moved into and outof alignment with apertures 64 of first plate 62 to thereby open andclose valve 60. The chassis is preferably configured as furtherdiscussed below, to guide and possibly retain second plate 66 adjacentthe first plate 62. As shown in FIGS. 5A and 5B, a lubricating layer 69made of oil or TEFLON® may be disposed between plates 62 and 66 toenable second plate 66 to more readily slide along the surface of plate62. Thus, lubricating layer 69 enables the valve to be opened and closedrequiring less force by the actuator. In addition, because it may bedifficult to get the surfaces of plates 62 and 66 to be sufficientlysmooth so as to provide a good seal, the lubricating fluid 69 may beutilized to enhance the sealing characteristic of the valve withoutrequiring complex and expensive machinery of the plates to otherwisefurther smooth their surfaces. Second plate 66 may be made of a magneticmaterial, such as that commonly used in the gaskets provided onrefrigerators. By utilizing a magnetic plate 66, chassis 70 does notneed to be configured so as to include any mechanism for otherwiseholding plate 66 firmly against plate 62. The magnetic plate 66 ispreferably a flexible magnet that can conform to the shape of adjacentplate 62. Magnetic plate 66 can be made from suitable magnetic material,such as a blend of ferromagnetic (e.g., barium/strontium ferrite) andelastomeric materials. The magnetic plate 66 can be a permanent magnetthat does not consume energy from the cell 20 to maintain sufficientmagnetic force. In the embodiments shown in FIGS. 3 and 11, moveablesecond plate 66 can be constrained on the top and bottom by a lid 100(as described further below) and bottom surface 35 of can 34. In analternative embodiment, battery 10′ has a fluid regulating system 50′shown in FIGS. 23 and 24. The chassis 70′ is taller than chassis 70 inFIGS. 3 and 11. This can facilitate the movement of fluid between thelid 100 and the moveable plate 66, thereby providing more uniformdistribution of fluid across the surface of plate 66 and more uniformflow of fluid through apertures 68 and 64 when plates 66 and 62 arealigned in an open position.

Chassis 70′ can include an inward extending ledge 71, creating a race orgroove 73 within which plate 66 can slide. The vertical position ofledge 71 can be selected to create a race 73 of the desired dimensionsto hold plate 66 firmly enough against surface 35 to provide a good sealwhen plates 66 and 62 are aligned in a closed position but not sotightly as to interfere with the desired sliding motion of plate 66.Ledge 71 can be an integral part of chassis 70′, or it can be a separatecomponent. For example, ledge 71 can be in the form of a flat washer orstrip insert molded into the chassis body 72′, or it can be a separatecomponent affixed to the chassis body 72′. The ledge 71 can be made ofthe same material as chassis body 72′ or a different material. Materialsfor the chassis body 72′ and ledge 71 can be selected to provide boththe desired strength and smooth sliding of plate 66 within the race 73.If either the chassis body 72′ or ledge 71 is made from an electricallyconductive material, insulation from the electrical components of theactuator 80 and control circuit 90 may be required. As an alternative toa continuous ledge, a series of projections can be used.

The ledge 71 and/or chassis body 72′ can also be modified to incorporateone or more additional structures, such as ribs extending across theopening 74′ above plate 66, to hold the central portion of plate 66flat. Alternatively, downward projections from the lid 100 can be usedto hold the central portion of plate 66 flat.

The chassis 70′ can include a second race 77 in which the lid 100 isheld, as shown in FIG. 25. This second race can be formed by one or moreadditional ledges 79 a and 79 b. This arrangement can facilitatepre-assembly of the lid and components of the fluid regulating system,to be added to the fluid consuming cell at another step in themanufacturing process. In another embodiment in which the stationaryplate 62 is not a surface 35 of the can 34, the chassis 70′ can includeanother ledge (not shown) below ledge 71, forming a larger race thatretains the stationary plate 62 as well as movable plate 66.

The ledge 71 of chassis 70′ can be a continuous ledge extending aroundthe entire perimeter of opening 74′, or it can be a discontinuous ledgeextending along only part of the perimeter, as shown in FIG. 23. If thediscontinuous ledge is suitably located and the moving plate 66 issufficiently flexible, if the pressure within the cell becomesexcessive, the edge of the moving plate 66 can bow outward between theends of the discontinuous ledge 71 to provide a passageway between theplate 66 and both plate 62 and chassis frame 72′ through which gases canescape to the external environment when the valve is partially open orclosed. In such embodiments the plate 66 preferably has spring-likeproperties so that when the internal cell pressure is sufficientlyreduced, the plate 66 will again conform to the shape of the surface 35of the can 34.

In an alternative embodiment in which the lid serves as the stationaryvalve plate and the moveable plate is disposed adjacent to the lid, thechassis can include a ledge to hold the moveable plate against the lidwhile maintaining a space between the moveable plate and the surface ofthe can bottom, to facilitate uniform air distribution to the aperturesin the can. As described above, this embodiment can also include asecond race in the chassis in which the lid is held.

The fluid regulating system can be actuated in response to the voltageof the fluid depolarized cell, as described below, or it can be actuatedby the user, or a combination of methods can be used. For example, whenthe user of a device powered by the cell device turns the device switchto the on position, the valve can be initially opened by mechanicalaction, and when the user turns the device switch to the off position,the valve can be initially closed by mechanical action. While the deviceswitch remains in the on position, a control circuit can control theoperation of the valve. In another example, when the device is turnedon, power from the cell can be applied to the fluid regulating system toinitially open the valve, and when the device is turned off, the valvecan be actuated to close.

An actuator is preferably provided as a part of fluid regulating system50 to actuate valve 60. The actuator may include a control circuit 90that senses the voltage of fluid consuming cell 20 and which generates acontrol signal in response to the detected cell voltage. Circuit 90 maybe an application specific integrated circuit (ASIC), which ispreferably mounted on a surface of chassis 70. The body 72 of chassis 70is preferably made of a non-conductive material such that tracings 96and 98 may be printed on a surface of the chassis as further discussedbelow. Chassis 70 may thus be a printed circuit board. The chassis couldbe molded or shaped and most or all of the electrical connections couldbe pressure contacts to minimize the complexity of assembly. The chassismay, however, require some machining, and some electrical connectionsmay require some soldering or welding. The selection of the chassismaterial may be based on its compatibility with its multi-functional useas a frame to house the valve, as a printed circuit board for theelectronics, and for its ability/compatibility to be secured to oragainst the cell, battery casing or device. A strategic depression maybe provided in and/or on a laminar structure of the chassis for mountingthe control circuit 90. This can allow mounted parts to be maintainedflush with the surface of the chassis to facilitate assembly with thecell. It is also possible that it may become desirable to coat theprinted circuit tracings, such as tracings 96 and 98, with anonconductive material to prevent shorting if pressed against a metallid 100 or can 34. Alternatively, one or more recesses may be providedin the chassis, such as by molding or machining, to accommodate all or aportion of one or more components of the control circuit and theactuator. These recesses can be useful to allow positioning ofcomponents in different locations on the chassis and anchoring ofcomponents that extend beyond the chassis frame, as described below.

As a platform for the electronics, it would be desirable for the basematerial of chassis 70 to be an existing PCB material. The most commonbase materials contain epoxy resins and fiberglass reinforcement. It maybe desirable for chassis 70 to be of laminar construction to integrateand protect the electronic circuit components, as well as to maintain aflush surface, parallel with bottom surface 35 of can 34. As describedabove, the inside diameter of the chassis may utilize a metal race fordurability to house sliding valve plate 66. The race may “lock” plate 66in place (so it does not fall out), provide enough axial force toprevent the valve from separating during use but insufficient force toprevent plate 66 from sliding. The chassis may thus be formed, molded,or machined, dependent on the material selection, so as to achieve thevalve race shape, whether metal or not, to flush mount a chip and togenerate vias (through-holes). There may be conductive circuitry withinthe vias, on one side and an edge of a chassis if mounted external tothe cell, or on both sides of chassis 70 if mounted internal to thecell.

A conductive pathway for circuit 90 may be provided on both sides ofchassis 70 and within the vias. This may be accomplished by a platingprocess or screen printing a conductive paste, especially to fill thevias. Conductive foil could be applied to the substrate at formation andthe unwanted portion etched away. Copper is the most common materialused. It may require multiple layers and multiple materials to assureadherence to the substrate depending on the base material utilized.

One method of attaching an ASIC serving as control circuit 90 is to usea direct method, as opposed to a packaged chip, due to volumeconstraints. Common methods of direct chip attachment include wirebonding, flip chip and other known techniques. According to oneembodiment, wire bonding could use wires about 0.02 mm (0.0008 inch) indiameter that are bonded to the four to six chip pads and the circuitsubstrate. According to a flip chip embodiment, the packaged flip chipmay be attached with solder bumps that form the physical and electricalconnections. The chip and wire bonds may be encapsulated innon-conductive epoxy for protection. With a flip chip attachment, thepads may be pre-finished with a Pb/Sn solder and, in turn, soldered tothe substrate. Once attached, the chip may be encapsulated withnon-conductive epoxy to provide protection.

In the embodiment shown in FIGS. 3 and 4, the actuator further includesa plurality of shape memory alloy (SMA) components that particularlyinclude a first SMA wire 82 a and second SMA wire 82 b. The SMA wiresare secured at either end of the chassis 70 and are electrically coupledto tracings 96 and 98, which extend from control circuit 90 to anopposite side of chassis 70. By supplying a control signal that passes acurrent through SMA wires 82 a and 82 b, the control circuit 90 maycause the SMA wires to heat up, which causes the SMA wires to expand orconstrict to a particular length. This in turn causes the SMA wires 82 aand 82 b to pull second plate 66 in one direction or opposite directionand thus causes plate 66 to slide in and out of an open or closedposition so as to selectively allow fluid (e.g., air) to pass into theinterior of cell housing 30.

As shown in FIG. 4, two contact terminals 92 and 94 are provided onchassis 70 for connection to the positive and negative terminals of cell20. The contact terminals 92 and 94 may be provided on any surface ofchassis 70, and as discussed below, it may be preferable to provide oneof the contact terminals, particularly terminal 94, on an outer facingedge surface of chassis 70 such that it may be exposed to the outside ofthe battery assembly for subsequent connection to the cover 36 of cell20. Contact terminal 92, on the other hand, may best be provided on aninner surface that is either pressed into electrical contact with aconductive portion of lid 100 or on the opposite surface in electricalconnection with the bottom surface 35 of can 34. The manner by whichelectrical connections of contact terminals 92 and 94 are made to can 34and cover 36 of cell 20 are discussed further below.

As shown in FIG. 3, fluid regulating system 50 may further include a lidor cover 100 that extends over and optionally around chassis 70 toprotect and shield fluid regulating system 50. Lid 100 preferablyincludes one or more holes 102 to allow fluid to pass from the outsideto valve 60 for selective passage into cell 20. As mentioned above, lid100 may serve as first plate 62.

In one embodiment, the valve 60 is in an open condition when a currentis applied indicating that cell 20 is in use, and is closed when acurrent is not applied indicating that the cell is not in use. In theembodiments discussed with respect to FIGS. 3, 4, 6, 11, 26 and 27A-Dthe SMA wires 82 a-82 e pull, but do not push the second valve plate 66.Thus, in FIGS. 3 and 4 first SMA wire 82 a pulls the valve open, whereassecond SMA wire 82 b pulls the valve closed. The SMA wires 82 may bedisposed in parallel and are provided in a symmetric fashion about acenter point of the valve plate 66 so as to supply an even force toprevent plate 66 from binding within chassis 70. In general, when thecurrent applied to the SMA wires is provided from the cell it can beadvantageous for current to be applied only to initiate movement of theactuator and not while the actuator is in a static condition in order toprevent unnecessary use of cell capacity. As shown, the SMA wires may bemounted to extend substantially parallel to one another. The SMA wiresmay also be mounted to extend parallel to the direction in which plate66 moves (see e.g., FIG. 3) or perpendicular to the direction in whichplate 66 moves (see e.g., FIGS. 6, 7 and 8).

SMA wires may be made with any conventional shape metal alloy. A shapememory alloy is an alloy that can be deformed at one temperature butwhen heated or cooled returns to its previous shape. This propertyresults from a solid phase transformation, between the Martensite andAustenite phases. Preferred shape memory alloys have a two-way shapememory; i.e., the transformation is reversible, upon both heating andcooling. Examples of shape memory alloys include nickel-titanium,nickel-titanium-copper, copper-zinc-aluminum and copper-aluminum-nickelalloys. The use of nickel-titanium-copper (e.g., with about 5-10 weightpercent copper) can be advantageous for actuators that may be operatedmany times because of its resistance to fatigue. Manufacturers ofnickel-titanium and other shape memory alloys include Specialty Metals,Shaped Memory Alloy Division (New Hartford, N.Y., USA), MemoryCorporation (Bethel, Conn., USA), and Dynalloy, Inc. (Mesa, Calif.,USA).

FIG. 6 shows another manner to attach to SMA wires 82 a and 82 b inorder to move plate 66. According to this variation, SMA wires 82 a and82 b are not provided to extend along the longest dimension of the plate66, they instead are substantially perpendicular to the direction ofmovement of plate 66. The first wire 82 a may be heated to cause firstwire 82 a to contract, while second wire 82 b is not heated allowingthat wire to flex. Thus, the plate 66 may be shifted in a firstdirection (to the right in FIG. 6 as shown with solid lines). To movethe plate in the opposite direction (i.e., to the left), a current maybe removed from wire 82 a thus allowing wire 82 a to cool and flex,while a current may be applied to wire 82 b thus heating wire 82 b andcausing it to contract. This causes the plate and wires to move to theposition shown in dashed lines in FIG. 6.

The chassis 70 is shown having control circuit 90 and circuit tracesformed on the top surface of the chassis body 72. Additionally, the SMAwires 82 a and 82 b are attached to a top surface of the chassis 70 inelectrical contact with the circuit traces. The chassis 70 is furthershown in FIG. 6 having an overmold body 300 formed over the controlcircuit 90 and circuit traces so as to encapsulate and protect thecomponents provided on chassis 70. Thus, the overmold body 300 serves aspart of the chassis 70. The overmold body 300 may include anon-conductive epoxy or other overmolding material. Additionally, theovermold body 300 is further shown including integrally formed ribs 302which extend across the opening 74 above moving plate 66. The ribs 302are shown formed in a generally V-shape and serve to hold the centralportion of the moving plate 66 flat above the underlaying fixed plate62. In one embodiment, the fixed plate 62 is connected to the bottomside of chassis 70 or its overmold body 300 and the battery cell isconnected to the top side of the overmold body 300 of chassis 70.

In the embodiment shown in FIG. 6, the first and second SMA wires 82 aand 82 b engage separate actuator pins 304 a and 304 b, respectively,which are connected to the moving plate 66. In the embodiment shown inFIG. 7, a single actuator pin 304 may be utilized in the fluidregulating system 50. With a single actuator pin 304, the first SMA wire82 a engages one side of pin 304, while the second SMA wire 82 b engagesthe opposite side of pin 304, such that SMA wires 82 a and 82 b actuatepin 304 in opposite directions to move plate 66 left and right to openand close the valve. In this embodiment, the actuator pin 304 mayinclude wire receiving portions, such as detents or slots, at differentelevations to engage the corresponding SMA wires 82 a and 82 b atdifferent heights, such that the SMA wires 82 a and 82 b do not contactor otherwise interfere with each other.

Referring to FIG. 8, an alternate actuator pin 304 is shown employed ina fluid regulating system 50, according to another embodiment. Pin 304is shown including first and second portions 306 a and 306 b that areelevated above the remainder of the generally rectangular pin 304 suchthat the SMA wire 82 a engages portion 306 a and SMA wire 82 b engagesportion 306 b. Portions 306 a and 306 b may include upstanding membersas shown. Alternately, portions 306 a and 306 b may include slots formedwithin a pin or other structure 304. Accordingly, single or multipleactuator engagement structures may be employed to allow the SMA wires 82a and 82 b to actuate the moving plate 66 in either direction to openand close the valve.

FIGS. 9A and 9B show two side views of valve 60 used adjacent an outersurface of can 34. FIG. 9A shows a cell at rest in which case valve 60is closed so that the apertures 64 and 68 do not align. FIG. 9B showsthe position of the valve's second plate 66 when moved into an openposition which would occur when the cell is in use. This causesapertures 64 and 68 to align and thereby allows fluid to pass into theinterior of the cell. As illustrated, SMA wires 82 a and 82 b may beattached to chassis 70 by means of a pair of spring contacts 76 to whichthe SMA wires may be crimped, clamped, soldered or welded.

FIG. 10 shows another embodiment of valve 60 that may be utilized invarious embodiments of the present invention. Valve 60 includes firstplate 62 including a plurality of apertures 64. Plate 62 may be aseparate plate that is held stationary relative to chassis 70 or may bea portion of the can or cover of a cell housing 30. Plate 62 may be madeof metal, which may be magnetic or non-magnetic. Valve 60 furtherincludes second plate 66 including a plurality of apertures 68 thatcorrespond in number, size, shape, and position to apertures 64 andfirst plate 62. Plate 66 may be a magnetic or non-magnetic metal.Similar to the embodiments discussed above, a chassis 70, whichpreferably is made of an electrically non-conductive material, includesan annular body 72 with a central opening 74 for receiving plate 66.Opening 74 is configured to be slightly larger than plate 66 in onedirection so as to enable plate 66 to slide linearly relative to plate62 such that apertures 64 and 68 may be moved into and out of alignmentto open and close valve 60. The implementation shown in FIG. 10 differsfrom the implementations discussed above insofar as a lever arm 84 isutilized as a part of actuator 80. Lever arm 84 includes a pivot pin 86that is received in an aperture or a slot or recess 78 formed in chassis70 such that lever arm 84 may be pivotably secured to chassis 70. Thismay be done, for example, by enlarging and reshaping the recess 78 tofit around pivot pin 86 and partially extend into the necked areabetween the pivot pin 86 and the body of lever arm 84 in such a way asto capture pivot pin 86 within the recess 78 but still allow the leverarm 84 to pivot within the recess 78. Other means of securing the pivotpin 86 to the chassis may be used, such as a downward projection frompivot pin 86 that is received in a hole in a ledge at the bottom of therecess 78. An actuator pin 88 preferably extends downward from the bodyof lever arm 84 such that it may be received in a hole 67 formed insecond plate 66. This allows lever arm 84 to engage plate 66 and thus toslide second plate 66 relative to first plate 62. In this particularconfiguration, a pair of SMA wires 82 a and 82 b is attached via anattachment point 89 to a top surface of lever arm 84. The other ends ofwires 82 a and 82 b may be attached to chassis 70. Wires 82 a and 82 bcan be secured to recesses in the chassis, similar to recess 78, forexample. They can be secured in any suitable manner, such as withadhesives, with pins or by fitting enlarged heads into recesses withrestricted openings. The SMA wires are electrically coupled to a controlcircuit (not shown in FIG. 10) that selectively applies a current to SMAwires 82 a and 82 b in response to a sensed cell voltage. In thismanner, SMA wires 82 a and 82 b may pull the lever arm in either of twoopposing directions thus causing lever arm 84 to slide second plate 66relative to first plate 62. In this case, chassis 70 serves as amounting location for the pivot point of lever arm 84 and of the ends ofSMA wires 82 while also providing a guide for guiding plate 66 relativeto plate 62.

Other arrangements of SMA wires and levers can be used to operate avalve in a fluid regulating system. For example, SMA wires 82 a and 82 bcan be attached to lever arm 84 via two separate attachment pointsrather than a single attachment point 89.

SMA wires can be connected to components of a fluid regulating system inany suitable manner. In one embodiment one or both ends of an SMA wire82 are captured within a suitably sized connector 87, as shown in FIG.28. Preferably the SMA wire 82 is crimped into the connector 87.Optionally the wire can be glued, welded or soldered to the connectorbefore or after crimping. The connector can then be inserted into acorresponding aperture in the component (e.g., chassis 70 or lever arm84) to connect the SMA wire 82 to that component. Preferably theconnector 85 is electrically conductive and can make electrical contactbetween the SMA wire 82 and a portion of the control circuit disposed onthe surface of the component defining the aperture. The connector 87 canbe held in place within the aperture by an interference fit, anelectrically conductive adhesive, solder or a weld, for example.

In embodiments in which a control circuit is used to restrict the flowof current through the SMA wire(s) to only the time required to move thevalve to an open or closed position, the SMA wires can return to theiroriginal length (e.g., elongate) after the current flow is stopped. Whenthis happens, the SMA wires may not hold the plate in the desiredposition, allowing it to slide to a partially open or partially closedposition, for example. This is particularly true when there is anopposing SMA wire for moving the sliding plate to another position;elastic tension from the unactuated opposing SMA can pull the slidingvalve as the actuated SMA elongates following the cessation of current.In such situations, the sliding plate can be held in the desiredposition until the plate is intentionally moved from that position. Anexample of a means of retaining the sliding plate in a desired positionis a latching mechanism. Any suitable mechanism can be used. In oneembodiment a spring biased detent can cooperate with a projection fromor a recess in a surface of the sliding plate. The spring force can beselected to be sufficient to keep the plate from sliding unintentionallybut weak enough to be easily overcome by the action of an opposing SMAwire to slide the plate into another desired position.

In another embodiment, the sliding plate is kept from slidingunintentionally by friction between the sliding plate and another cellor fluid regulating system component. The friction between the plate andthe other component is sufficient to prevent unintentional sliding butnot so great as to interfere with the efficient movement to anotherposition by action of an opposing SMA. The friction can be controlledthrough the selection of materials for the sliding plate and the othercomponent, a coating applied to one or both parts, or the texturing ofone or both of the adjacent surfaces.

The fluid regulating system 50 may be secured to the exterior of cell 20using a variety of techniques that are discussed below. As shown in FIG.11, lid 100 may be configured to have a plurality of stand-offs 104 thatextend downward from an inner surface of lid 100 and then pass throughholes 75 in corresponding locations on chassis 70 such that thestand-offs 104 may be attached to bottom 35 of can 34. FIGS. 12 and 13show two different constructions for the configuration shown in FIG. 11.

In FIG. 12, a configuration is shown whereby the lid 100 is formed ofplastic. In this case, the stand-offs 104 may be ultrasonically weldedto the bottom surface of can 34. In this case, there would be noelectrical connection between the lid 100 and can 34.

In FIG. 13, the stand-offs 104 are provided as an indentation/protrusion106 in a metal lid 100 which may be formed by stamping or the like. Inthis case, the metal lid 100 may be resistance- or laser-welded to thebottom surface 35 of can 34.

FIG. 14 shows an alternative method of connecting chassis 70 and lid 100to the exterior of cell 20. In this case, vias 105 are provided throughthe holes 75 of chassis 70 which serve to weld lid 100 to can 34. Thisweld also provides an electrical connection between lid 100 and cell 20.

FIG. 15 shows yet another technique whereby a metal lid 100 is securedto can 34 using a conductive epoxy 107 that is provided in the holes 75of chassis 70. As yet another alternative, the fluid regulating system50 may be secured to the bottom surface of can 34 using an adhesive, acombination of an adhesive and a label (not shown), by means of a pressfit of the chassis into one or more grooves coined in the bottom surfaceof can 34, by such a press fit of the chassis in addition to utilizingan adhesive, by crimping can 34 within a second can where the secondoutermost can replaces lid 100, by soldering or welding a laminarchassis, or encapsulating the fluid regulating system 50 in an epoxy.

It should be appreciated that various other alternative actuators andvalves may be employed in the fluid regulating system. Examples ofvarious actuators and valves employed in a fluid regulating system aredisclosed in U.S. patent application Ser. No. 11/860,117, filed on Sep.24, 2007, the entire disclosure of which is hereby incorporated hereinby reference. Although the use of SMA wires has been described above asbeing a preferred component of actuator 80, other components ormaterials may also be utilized, such as linear electrode-active polymers(EAPs) and bending electro-active polymers (EAPs), which are associatedwith artificial muscles. Such materials offer potential advantagesincluding a simpler design, no or simplified electronics, and aproportional response to voltage. Examples of electro-active polymers(EAPs) are disclosed in U.S. patent application Ser. No. 11/852,516,filed on Sep. 10, 2007, the entire disclosure of which is herebyincorporated herein by reference.

Another consideration relates to the initial activation of the battery.The battery may be built with the valve in the open position and withholes 102 protected by a tab similar to conventional button air cells.Air-up after removal of the tab would activate the cell, initiateelectronic control of the valve, and maximize the shelf life of thebattery. Alternatively, the battery could be built with a functioningfluid regulating system. This would allow the battery to be immediatelyuseable by the consumer but may also require suitable packaging andstorage conditions in the warehouse, store shelves, etc. to preventmoisture ingress in humid environments and moisture egress in dryenvironments.

In the construction discussed above, the can 34 is proposed to act asthe stationary plate 62 of valve 60. However, it may be desirable toprovide a separate fixed plate 62 rather than utilizing can 34 such thatthe can bottom will maintain its hole pattern, but may act more like anair diffuser rather than an integral part of the valve assembly. Inaddition, the stationary plate 62 may be spaced apart from the canbottom such that if the can 34 bulges, bows, or possibly wrinkles, itwill not disrupt the operation of the valve 60. It should be noted thatthe can 34 may be made with a stronger material, a greater thickness, ora different shape (e.g., ridges in the bottom). An additional advantageof utilizing a separate stationary plate 62 is that the valve 60 may betotally preassembled thus providing a greater stability of thelubricating fluid layer 69. This may come, however, at the cost of athicker battery.

Although not illustrated in the drawing figures, a label may be providedto the outer surface of cell housing 30. Such a label may extend aroundthe perimeter of the cell so as to further cover the electricalconductor tab 110 (discussed below) as well as the interfaces betweenthe fluid regulating system 50 and cell 20 and to cover the interfacebetween the can 34 and cover 36. Sufficient portions of the cover 36 andthe can 34 and/or a conductive lid 100 could remain exposed to provideelectrical contact terminals on the outside of the battery.

The particular cell construction illustrated in FIGS. 1-3 is a prismaticcell design. The construction differs from a conventional button-typeair cell in the relative size and rectangular nature of this cell.Similar air electrodes, anodes, separators and can/cover materials maythus be utilized in cell 20 that are presently used in conventional aircells. It should be appreciated by those skilled in the art, however,that the cell 20 need not have the particular shape, size, or relativedimensions as that shown in the drawings.

FIG. 16 shows an alternative embodiment of the present invention wherebythe fluid regulating system 50 is disposed in the interior of cellhousing 30. FIG. 17 shows a cross-sectional view of a portion of thisembodiment. As shown in these figures, the cell housing is constructedin a similar manner to that described above with the exception that thecell may be slightly thicker to accommodate the fluid regulating system50 between air electrode 40 and the inner surface of can 34. In thisembodiment, a chassis 70 may also be utilized along with a valve,actuator, and control circuit 90 as described above when applied to theexterior of the cell. Similarly, the bottom of can 34 may serve as firstplate 62 of valve 60 and may include a plurality of fluid entry ports 32which serve as apertures 64. This embodiment differs in that respectinsofar as the second plate 66 slides along the inner surface of can 34rather than the exterior surface. In this and other embodimentsdiscussed below, the chassis 70 and hence the valve 60 may be held inplace by gasket 38.

One other difference in the construction of the cell 20 when an internalfluid regulating system 50 is utilized is that the cell should bereconfigured to allow electrical connection of both the negative andpositive contact terminals of the cell to the control circuit 90 of theactuator. One manner of making this electrical connection is shown inFIGS. 16-18. As shown in FIG. 16, a contact opening 39 is formed in thebottom surface 35 of can 34. As shown in FIG. 17, the negative contactterminal 94 is provided at a bottom of chassis 70 through a via in thechassis so as to be exposed through opening 39. In this manner, anelectrical conductor 110 may be electrically connected to cover 36 ofcell housing 30 and extend around the outside of cell 20 to the opening39 while making electrical contact with contact terminal 94. Thisprovides a connection to the negative terminal of the cell. As alsoshown in FIG. 17, the positive contact terminal 92 provided on chassis70 may be positioned so as to contact an inner surface of can 34 so asto provide a connection to the positive terminal of the cell. Asdiscussed above, contact terminals 92 and 94 may be electricallyconnected to a control circuit 90 for controlling the actuator to openand close the valve in response to a detected cell voltage or currentdraw.

As shown in FIG. 18, electrical conductor 110 may be a tab that includesa foil strip 112 that is disposed between two insulative layers, whichprevent a short circuiting of the cell between can 34 and cover 36. Afirst insulative layer 114 may be disposed between the cell housing 30and conductive foil 112. This insulative layer 114 may be made ofdouble-sided tape. The second and outer insulative layer 116 may bedisposed over the foil and may comprise a strip of single-sided tape.Although this particular external electrical connection is shown withrespect to an internal fluid regulating system 50, the same electricalconductor 110 may be applied to provide an electrical path between cover36 and a similar contact terminal 94 of the external fluid regulatingsystem shown in FIGS. 1-3. In this case, an aperture similar to contactopening 39 could be formed in lid 100 or alternatively the electricalconductor 110 may simply extend between the interface between chassis 70and can 34 or the interface between chassis 70 and lid 100.

FIGS. 19-22 show yet another manner by which electrical connection maybe made between cover 36 and terminal 94 on chassis 70. In thisembodiment, a portion of the inner surface of can 34 is coated withthree layers of materials as best shown in FIG. 20. The first layer isan electrical insulator layer 151, the second layer is an electricallyconductive layer 153 that is applied over insulator layer 151 such thatthere is no electrical connection between can 34 and conductive layer153, and the third layer is an electrically insulating layer 154 appliedover a portion of conductive layer 153 to insulate the edge of the airelectrode 40 from the conductive layer 153. As shown in FIG. 20, layers151 and 153 extend around the inner bottom corner(s) of can 34 andextend over just enough of the bottom of can 34 so as to physicallycontact terminal 94 formed on the opposing surface of chassis 70. Asmentioned above, chassis 70 may be pressed against the inner bottomsurface of can 34 by gasket 38 so that the contact between conductivelayer 153 and contact 94 is by way of such pressure. Layers 151 and 153extend up a sidewall of can 34 between an interface of can 34 and gasket38. As best shown in FIGS. 19, 21 and 22, gasket 38 may include anaperture 155 through which a rivet or pin 157 may extend. Rivet or pin157 forms an electrical connection between cover 36 and conductive layer153 through gasket 38, thereby completing the conductive path betweencover 36 and contact 94 on chassis 70. Rivet/pin 157 may be molded inplace in gasket 38. Further, more than one such rivet/pin 157 may beused. The rivet/pin 157 may have a length sufficient to allow for gasketcompression. Layers 151, 153 and 154 are in the form of a strip as shownin FIG. 20 in order to allow the edge of the air electrode 40 to makeelectrical contact with the inside surface of the can 34. It should beappreciated that other electrical connections may be employed accordingto other embodiments.

As described above, the fluid regulating system can use electroniccontrols to operate the valve, based in part on the cell (or battery)voltage. However, a switch can be used to close an electrical circuitthrough an actuator that changes length to move the valve to an open ora closed position, with the circuit subsequently being broken to stopthe flow of current through the actuator when the valve reaches the fullopen or closed position. This can eliminate the need for more complexcontrol circuits, while still drawing energy from the cell only whenneeded to open or close the valve. The switch can be on or within thebattery itself, or it can be a part of the device in which the batteryis used. In one embodiment, the device on/off switch also alternatelycloses the circuits through opposing actuators to open and close thevalve. The operation of such a fluid regulating system is illustrated inFIGS. 27A-27D.

FIG. 27A includes a top view of a valve 260 similar to the valve 60shown in FIG. 3. Valve 260 includes a moveable plate 266 slidablydisposed in a chassis 270. Moveable plate 266 is shown in FIG. 27A inthe closed position (i.e., with apertures 268 out of alignment withapertures in a fixed plate). SMA actuators 282 a and 282 b are anchoredto the moveable plate 266 and opposite ends of the chassis 270 and areused to pull the plate 266 open and closed, respectively. Actuators 282a and 282 b are anchored to plate 266 via flat electrical contacts 277 aand 277 b, respectively, and to chassis 270 via electrical contacts 292a and 292 b, respectively. Flat contacts 277 a and 277 b are locatednear opposite ends of the top surface of plate 266 so they will makeelectrical contact with spring contacts 276 a and 276 b, respectively,when the plate 266 is in the open and closed positions, respectively.Spring contacts 276 a and 276 b also serve as contact terminals formaking connections to the remainder of a control circuit 290, which isrepresented schematically. The control circuit includes an on/off switch295 and the fluid depolarized battery 210 for providing electricalenergy to the device. When electrical energy is not required from thebattery 210, the switch 295 is in the off position and the valve 260 isin the closed position, as shown in FIG. 27A. Because neither of thecircuits including actuators 282 a and 282 b is closed, no current willflow through them, so the actuators 282 a and 282 b are at an ambienttemperature and in an elongated condition.

When the switch 295 is moved to the on position, current flows throughactuator 282 b, causing it to heat, shorten and pull plate 266 to theleft toward the open position. When plate 266 reaches the open position,as shown in FIG. 27B, the electrical connection between contacts 276 band 277 b is broken. When the circuit is broken, current ceases to flowthrough actuator 282 b. This accomplishes two things. First, noadditional energy is drawn from the battery 210 while the device remainsturned on, and second, actuator 282 b cools and returns to an elongatedcondition, as shown in FIG. 27C, so the plate 266 can be moved back tothe left when the device is turned off. When the switch 295 is moved tothe off position, the circuit that includes actuator 282 a is closed,and the flow of current therethrough causes it to shorten and pull theplate 266 to right, toward the closed position. When the plate 266reaches the closed position, the electrical connection between contacts276 a and 276 b is broken, as shown in FIG. 27D, and current ceases toflow through actuator 282 a, allowing the actuator to cool and elongate,as shown in FIG. 27A.

Electrical connections to contacts 276 a, 276 b, 277 a and 277 b can bemade in any suitable manner. For example, connections can be madethrough the chassis 270 or through an interface between the top surfaceof the chassis 270 and the corresponding surface of an adjacentcomponent, such as a lid covering the chassis 270 and valve 260, to theedges of the fluid regulating system. In another example, electricalconnections can be made through suitably placed contacts extendingthrough a lid covering the valve 260. A switch that is part of the cellcan be affixed to a suitable surface of the cell and/or fluid regulatingsystem, such as on an exterior surface of a lid. Alternatively, a switchcan be located on an outer surface of a multiple cell battery, or withina device in which the battery is installed, with electrical connectionsto the fluid regulating system made in a suitable manner, such as bywelding, soldering or pressure between corresponding contacts. In otherembodiments, more than two actuators can be used.

Instead of incorporating the control circuit electronics within thefluid regulating system, they can be located externally. This may bedesirable in situations where they cannot be conveniently fitinternally, for example. In one embodiment the electronics can bemounted on an exterior side of the fluid regulating system, such aswithin a cap mounted on the side wall of the fluid regulating systemand/or the cell, as shown in FIG. 26. FIG. 26 shows a chassis 70,moveable plate 66, SMA wires 82 a and 82 b, and contact terminals 92′and 94 similar to those in FIG. 4. Unlike FIG. 4, however, the SMA wires82 a and 82 b in FIG. 26 are connected directly to the contact terminals92′ and 94, with no intermediate control circuit 90. The control circuitin FIG. 26 is contained in a circuit board 91 secured to the side of thechassis 70 with a cap 93 that protects the circuit board 91. The contactterminals 92′ and 94 on the chassis 70 make electrical contact withcorresponding terminals on the surface of the circuit board 91.Electrical contact can be made in any suitable manner, such as bypressure contact. The circuit board 91 can have a single substratelayer, or it can be a laminated substrate with two or more layers. Theelectronics components and electrical connections can include printed ornon-printed components, or combinations thereof. Larger components canbe disposed in recesses in the surfaces of the circuit board 91 toprovide flush fits with the chassis 70 and cap 93. The electricalconnections between the circuit board 91 and the cell are not shown, butthese connections could also be made through the chassis 70.

Referring to FIG. 29, a fluid regulating system 50 is illustrated forregulating fluid (e.g., air) to a battery by controlling the opening andclosing of the valve and further includes a passive temperature closure,according to a further embodiment. SMA wire 82 a may be electricallyenergized to heat up and contract and thereby move moving plate 66 tothe open valve position (as shown in FIG. 29) via actuator pin 304 a.SMA wire 82 b may be electrically energized to heat up and contract andthereby move moving plate 66 to the closed valve position via actuatorpin 304 b. The valve may therefore be actively opened and closed inresponse to electric current applied to either SMA wires 82 a or 82 b.Additionally, the SMA wires 82 a and 82 b are selected with differentactuation temperatures to provide a passive temperature closure of thevalve, according to one embodiment of the present embodiment. The SMAwires 82 a and 82 b have an unbalanced actuation temperature to achievethe desired passive closure of the valve. Thus, the moving plate 66 ismoved to the closed valve position upon experiencing a predeterminedtemperature limit.

In the embodiment shown and described in FIG. 29, the SMA wire 82 a isconfigured with a first actuation temperature of about 90° C., whereasthe SMA wire 82 b is configured with a lower second temperature of about60° C. When electrically energized, SMA wire 82 a heats up and contractsto apply force to actuate moving plate 66 to the open position uponreaching the higher first temperature. Similarly, SMA wire 82 b may beelectrically energized to heat up and contract to actuate the valve tomove moving plate 66 to the closed position at the lower secondtemperature. The first temperature is greater than the secondtemperature such that the SMA wire 82 b closes the valve when thetemperature of SMA wire 82 b reaches the lower second temperature. Itshould therefore be appreciated and in addition to actively opening andclosing the valve based on electrical current applied to the SMA wires82 a and 82 b, the SMA wire 82 b forces the moving plate 66 to theclosed valve position when the ambient temperature first reaches thelower second temperature. If the temperature of the environmentcontinues to rise to the higher second temperature, the SMA wire 82 awill not apply sufficient force to change the position of the valve fromits closed position.

SMA wires 82 a and 82 b may include commercially available SMAcomponents. One example of a 60° C. actuation SMA wire is a 0.102 mm(0.004 inch) diameter 60° C. wire, commercially available from Flexinol.One example of a 90° C. actuation SMA wire is a 0.076 mm (0.003 inch)diameter 90° C. wire, commercially available from Flexinol. In theexample given, the 60° C. SMA wire will remain contracted until thetemperature has dropped back down to about 40° C., thereby resulting ina temperature hysteresis.

The fluid regulating system 50 employing the unbalanced temperature SMAwires advantageously provides a passive method for closing the valve toprevent fluid ingress to the battery cell above a predeterminedtemperature. By closing the fluid regulating system 50 at apredetermined temperature, such as 60° C., degradation of the batterymay be minimized or prevented. Additionally, by moving the valve closedupon reaching a temperature limit, such as 60° C., opening of the valveat high temperatures is prevented. It should be appreciated that thepredetermined temperature for closing the valve may be greater than 45°C., and more particularly, may be set at about 60° C.

According to one embodiment, the SMA wires 82 a and 82 b may beconfigured having different sizes to generate different actuation forcessuch that the SMA wire 82 b generates a greater actuation force than theactuation force generated by SMA wire 82 a. In an exemplary embodiment,SMA wire 82 b has a greater cross-sectional area, such as a greaterdiameter, than SMA wire 82 a. With a larger cross-sectional area, SMAwire 82 b applies a greater closing force to the moving plate of thevalve in the event that the ambient temperature reaches the higher firsttemperature. It should be appreciated that the SMA wires 82 a and 82 bmay be circular in cross-section and the second SMA wire has the largerdiameter. According to other embodiments, the SMA wires 82 a and 82 bmay have other cross-sectional shapes, such as oval, square orrectangular shapes, with the second SMA wire 82 b having a greaterdimension, resulting in a greater cross-sectional area, which results ina greater actuation force than the first SMA wire 82 a. In anotherembodiment, SMA wires 82 a and 82 b may have both differentcross-sectional areas and different phase transition temperatures, suchthat SMA wire 82 b will generally be actuated first as the ambienttemperature increases, which results in the valve remaining closed evenas the ambient temperature rises above the higher phase transitiontemperature of SMA wire 82 a.

Referring to FIGS. 30-34, a fluid consuming battery 10 is shown having abattery cell 20 and a fluid regulating system 50 having a fluid passagethrough the chassis body 300 that provides for pressure equalizationbetween the cell 20 and the outside environment, according to twoembodiments. In the embodiments shown, a chassis is generallyillustrated by the overmold body 300 having a central opening 332 and aninward extending ledge 354. A fluid consuming battery cell 20, such asan air cell, is connected on the top surface of the chassis 300. Thefixed plate 62 with fluid entry ports 64 is connected to the bottomsurface of chassis 300 and moving plate 66 with ports 68 is disposedbetween the lower wall of inward extending ledge 354 and fixed plate 62so that plate 66 may be moved relative to plate 62.

In the embodiment shown in FIGS. 30-33, the overmold chassis body 300 isgenerally illustrated having a first port, also referred to as an inlet350, located generally between the cell 20 and the moving plate 66, andin fluid communication with opening 332 and cell 20. The chassis body300 also has a second port, also referred to as an outlet 352, providedon the outside of the overmolded material leading to the outsideenvironment. The overmolded chassis 300 is manufactured to have anonporous outside layer 360 and a porous internal volume that providesthe fluid passage 356. The nonporous outside layer 360 is generallynon-permeable to fluid, particularly air, and may include an epoxy,according to one example. The porous internal volume provides for apressure equalization fluid flow passage 356 that extends from the inlet350 to the outlet 352. The porous internal volume may include an airpermeable material, such as microporous polytetrafluoroethylenematerial, or a non-woven porous material that allows restricted air flowat a low diffusion rate through the passage 356. Alternatively, or inaddition, the fluid passage 356 may include empty void volume providinga sufficiently restricted passage that allows air flow at a lowdiffusion rate. The fluid passage 356 advantageously allows air toslowly pass from the inlet 350 to outlet 352, however, the fluid passage356 may allow fluid to pass in either direction between the inlet 350and outlet 352 to provide pressure equalization between the cell 20 andthe outside ambient environment.

The inlet 350 of fluid passage 356 is in fluid communication with theopen volume between the battery cell 20 and valve plates 66 and 62. Apressure differential existing between gases within the battery cell 20and outside environment may allow gas to migrate through the fluidpassage. When the battery cell 20 generates gas, the gas may migratethrough the restricted fluid passage 356 to the outside environment toprevent compromising the seal between the valve plates 66 and 62.Contrarily, gas may be permitted to flow from the outlet 352 to theinlet 350, but is generally restricted such that air is not freelysupplied to the battery cell 20 so that the cell 20 is generally notdischarged at a high rate when the valve is closed.

According to one embodiment, the fluid passage 356 has an air diffusionrate that would result in a loss of no more than ten percent (10%) ofthe cell capacity per year at room temperature due to moisture gain orloss. It should be appreciated that the porous volume of the fluidpassage 356 may include a membrane that is generally porous to gases toprovide a tortuous or restricted air flow passage, but does not allowfree unrestricted flow of fluid into the cell 20. According to oneembodiment, the porous volume 356 may include a tortuous fluid passage356, such as that provided by baffles 358 as shown in FIG. 33. Thebaffles 358 essentially increase the effective length of the airflowpassage 356 through the overmolded chassis 300, thus increasing the neteffective fluid flow path length. According to other embodiments, thetortuous fluid flow path may employ a honeycomb pattern that isgenerally porous to allow excess gas to escape from the cell 20 to theoutside environment, while minimizing the amount of air from enteringthe cell 20.

In the embodiment shown in FIG. 34, the top surface of the overmoldchassis body 300 has a slot 334 formed therein in a generally serpentineshape that extends from the inside opening 332 in a rectangular shapeabout the opening 332 by about 360° leading to the outside surface ofthe chassis 300. Disposed within the slot 334 is a hollow tube 336having a general configuration adapted to be sized and fit within slot334. The tube 336 has a first port, also referred to as an inlet 338, atone end in fluid communication with the inside opening 332 of thechassis 300 and cell 20, and has a second port, also referred to as anoutlet 340, at the other end in fluid communication with the outsideenvironment. The fixed plate 62 is shown connected on the bottom surfaceof chassis 300. The moving plate 66 is disposed below ledge 354 and isadjacent to and in sealed relationship with the fixed plate 62, suchthat plate 66 is moveable relative to plate 62 to open and close thevalve.

The tube 336 provided within chassis 300 provides a fluid passage thatextends between the inlet 338 and outlet 340 such that fluid releasedfrom the battery cell 20 is able to pass through the fluid passage oftube 336 to the outside environment. The fluid inlet 338 is located inposition in the volume of opening 332 between the battery cell 20 andthe fixed and moving plates 62 and 66, according to one embodiment.Thus, the extended length and small diameter of tube 336 provides atortuous fluid passage that allows fluid to escape from the cell 20 at asufficiently low diffusion rate, while sufficiently restricting airingress to the cell 20 due to the low diffusion rate. In one embodiment,tube 336 has a sufficiently restricted inner diameter of less than 0.5mm and an effective length of at least 200 mm. According to anotherembodiment, the slot 334 may be covered and utilized as the fluidpassage in lieu of use of the tube 336.

In the disclosed embodiments of FIGS. 30-34, a pressure differentialexisting between the gases within the battery cell 20 and the ambientoutside environment in which the cell 20 is exposed may cause adisruption, which may lead to subsequent failure of the fluid barrier.Thus, the intended primary seal barrier between the valve plates 62 and66 can be compromised, which would potentially allow uncontrolledingress and egress of fluid, such as water, oxygen, hydrogen, and carbondioxide, which could result in the unacceptable loss of batteryshelf-life. The pressure equalization fluid passage 336 or 356 providedin chassis 300 allows fluid such as gases to migrate through the fluidpassage to egress and ingress. By providing an appropriately sized holeof a suitable length, the fluid passage allows for the egress of gas,such as hydrogen generated within a metal-air cell, while prohibitingexcess ingress of oxygen and carbon dioxide to the cell 20.

Referring to FIGS. 35-49, a fluid consuming battery 10 is generallyillustrated having a fluid consuming battery cell 20 and a fluidregulating system 50 that includes a chassis 550 with an electricallyconductive frame 500 and components integrally formed therein, accordingto one embodiment of the present invention. The assembled battery 10having the fluid consuming cell 20 and fluid regulating system 50 isgenerally illustrated partially exploded in FIG. 35, and the assemblysteps are generally shown in FIGS. 36-49. According to this embodiment,the fluid regulating system 50 includes an electrically conductive frame500 having a plurality of electrical components 540, 542, 544 and 546assembled thereon. The electrically conductive frame 500 and theelectrical components 540-546 assembled thereon are substantiallyencapsulated within an electrically non-conductive chassis 550. Thechassis 550 is made of an electrically non-conductive material thatessentially covers the electrically conductive frame 500 and electricalcomponents as described herein.

The chassis 550 may include an epoxy or other electricallynon-conductive material that can be formed in the desired configurationto substantially encapsulate the electrically conductive frame 500 andthe electrical components 540-546 assembled thereon. The chassis 550 isformed having a shape that supports at least some of the components ofthe valve and connects to the battery cell 20. The frame 500 andelectrical components 540-546 can be substantially encapsulated by thechassis 550 using any suitable method, such as molding (e.g., insertmolding) or coating (e.g., by spraying, dipping, etc.). As used herein,substantially encapsulated means that the majority of the combinedsurface area of the frame 500 and electrical components 540-546 iscovered by the chassis 550, but portions of the frame 500 and/orelectrical components 540-546, such as electrical contacts and contactpads, can be exposed or extend from the chassis 550. The materials usedfor the frame 500 and chassis 550 can be selected such that thecoefficient of thermal expansion (CTE) of the frame 500 is substantiallysimilar to the CTE of the chassis. By matching the CTEs, the resultingframe and chassis structure is less susceptible to the creation ofleakage paths due to variations in expansion when the temperaturevaries.

As seen in FIG. 35, the valve is shown including a moving plate 66having a plurality of apertures 68 and a fixed plate 62 having aplurality of apertures 64. The chassis 550 generally defines a centralopening 555 and includes an inward extending ledge 552. The periphery ofthe moving plate 66 is positioned on and abuts the bottom surface of theinward extending ledge 552. Additionally, the chassis 550 has ribs 554which extend across the opening 555 above the moving plate 66. The ribs554 are shown generally formed in V-shape extending diagonally throughopening 555 and serve to hold the central portion of the moving plate 66flat above the underlying fixed plate 62. In the embodiment shown, thefixed plate 62 is connected to the bottom side of the chassis 550, andthe fluid consuming battery cell 20 is connected to the top side of thechassis 550. In this arrangement, fluid (e.g., oxygen and other gases)from the outside environment may enter the fluid entry ports of the cell20 by way of the valve when the valve is open.

The chassis 550 is further illustrated having crimp connector openings560 formed in desired locations and adapted to receive crimps 562 of theSMA wire actuators 82 a and 82 b. The crimp connector openings 560 maybe integrally formed during formation of the chassis 550 or may besubsequently formed by removing material (e.g., machining or etching) toform the desired opening shape and size. Extending from each of thecrimp connector openings 560 are respective circuit elements of theframe 500 that serve as contact pads 520. Contact pads 520 are formed aspart of the electrically conductive circuit elements of the frame 500and are adapted to make electrical contact with the SMA wire actuators82 a and 82 b to apply electrical current thereto. The frame 500 furtherincludes a plurality of circuit elements that serve as battery contacts530, 532, 534 a, 534 b, 536 a and 536 b extending from the chassis 550,each of which is adapted to be bent into contact with a terminal of thefluid consuming cell 20. The contacts 530, 532, 534 a, 534 b, 536 a and536 b can extend from the corners, as shown, or from other portions ofthe chassis 550.

The chassis 550 is further illustrated in FIGS. 35-41 having a pair ofposition sensors 600 located on the chassis 550, according to oneembodiment. The position sensors 600 are located on opposite ends of thechassis 550 for sensing position of the moving plate 66 of the valve. Inthe embodiment shown, one of the position sensors 600 senses position ofthe moving plate 66 relative to one end of the chassis 550 defining theopen valve position, while the other position sensor 600 senses positionof the moving plate 66 relative to the opposite end of the chassis 550defining the closed valve position. Thus, the position sensors 600 maybe used to sense when the moving valve plate 66 is in the open andclosed positions. One of the position sensors 600 is shown located in aposition where the moving plate 66 is expected to make contact with theposition sensor 600 when the moving plate 66 is in the open position.The other position sensor 600 is shown located in a position on theopposite end of chassis 550 where the moving plate 66 is expected tomake contact with the position sensor 600 when the moving plate 66 is inthe closed position. By sensing that the valve is in the open positionor closed position, the control circuitry may further enhance thecontrol of the valve of the fluid regulating system to achieve optimalfluid supplied to the fluid consuming electrode.

It should be appreciated that one or more position sensors 600 may beemployed to sense whether the valve is in at least one of the open andclosed positions. Additionally, one or more position sensors 600 maysense intermediate positions of the moving plate 66 of the valve betweenthe open and closed positions. The position sensors 600 may includelinear transducers, according to one embodiment. According to anotherembodiment, the position sensors 600 may include proximity sensors.Other embodiments of the position sensors 600 may include a lasersensor, an optical sensor, a microswitch position sensor, as well asother sensing devices that may indicate if the valve plate is in theopen position or closed position. Alternately, an indirect sensingmethod may include monitoring the battery cell voltage and determiningthe valve position based on the battery cell voltage, according toanother embodiment.

The position sensors 600 may be used to verify that the valve isactuated properly. According to another embodiment, a redundant set oftrigger points could be set in place of a valve position sensor. If thevalve fails to open properly, for example, the battery cell voltage maycontinue to drop below a first upper open voltage set point. Uponreaching a second lower open voltage set point, the valve may be sent asecond actuated pulse via the actuator assuming that the valve failed toopen the first time. If the position sensor indicates that the valve isnot in the proper location, a second actuation signal can be given toopen or close the valve. If the second actuation signal does not movethe valve, the assumption could be made that there is a more seriousproblem with the valve. Other more drastic measures could be employedsuch as sending a series of open and close signals to try to get thevalve to move. Assuming that the valve is stuck, the open and closesignals could rock the valve back and forth to free it from theobstruction. Alternatively, this information could be communicated backto the device and user if a communication capability exists.

The fluid regulating system 50 includes the valve actuator shown in thepresent exemplary embodiment made up of first and second SMA wires 82 aand 82 b. According to the embodiment shown, SMA wires 82 a and 82 b areconnected to lever 84 by way of arcuate slots 564. Specifically, thefirst SMA wire 82 a extends between end crimps 562 and one slot 564 andmay be activated to pull the lever 84 in one direction to open thevalve, while the second SMA wire 82 b is connected between end crimps562 and the other slot 564 to pull lever 84 in the opposite direction toclose the valve. Lever 84 includes an actuator pin 88 which engagesmoving plate 66 to move the plate 66 between the open and closed valvepositions as discussed herein. While the valve actuator is shown anddescribed herein employing two SMA wires 82 a and 82 b connected viarespective arcuate slots 564 to a lever 84, it should be appreciatedthat other types and arrangements of valve actuators may be employed toactuate the moving plate 66 relative to the fixed plate 62 to open andclose the valve. Further, it should be appreciated that while agenerally linear actuation of moving plate 66 is shown and describedherein, other configurations of valves may be employed to control theflow of fluid to the fluid consuming cell 20.

The assembly of the fluid regulating system 50 and battery 10 isillustrated in FIGS. 36-49. Referring to FIG. 36, the electricallyconductive frame 500 is generally illustrated therein, according to oneembodiment. The electrically conductive frame 500 is generally made ofan electrically conductive material that provides electricalconductivity and structural integrity for handling. The frame 500 may beimplemented as a lead frame, according to one embodiment. The frame 500includes electrically conductive circuit elements that are configured toconduct electrical current amongst various electrical components.

The frame 500 may include a nickel-iron alloy, according to oneembodiment. Examples of nickel-iron alloys include INVAR®, Super INVAR®,KOVAR®, and INVAR® alloys 36, 42, 46, 48 and 52. “True” INVAR® has theformula Fe₆₅Ni₃₅. For the INVAR® alloys, the alloy number correspondsapproximately to the weight percent of nickel. According to a morespecific example, the electrically conductive frame 500 may include anickel-cobalt ferrous alloy sold under the trade name KOVAR®, which isgenerally composed of approximately 29 percent nickel, 17 percentcobalt, 0.2 percent silicon, 0.3 percent manganese and 53.5 percentiron, by weight.

According to another embodiment, the frame 500 may be at least partiallycomposed of copper, and, more specifically, may be copper-INVAR®-copper.Copper-INVAR®-copper is a layered material with a layer of INVAR®sandwiched between layers of copper and has been used in printed circuitboard technology. It should be appreciated that other electricallyconductive materials may be employed in the frame 500 to achieve a framestructure that is electrically conductive and sufficiently rigid forhandling, and may be reshaped to form desired contact connections.

The frame 500 is shown having various circuit elements 522, 524, 526 andcontact pads 520 for supplying electrical current to electricalcomponents and the SMA wires 82 a and 82 b of the valve actuator.Additionally, the frame 500 includes circuit elements that serve asbattery contacts 530, 532, 534 a, 534 b, 536 a and 536 b which enableelectrical contact to be made with the positive or negative terminals ofthe battery cell 20. The frame 500 also includes contact pads 502, 504,506, 508, 510, 512, 514 and 516 which are generally configured toreceive electrical components and/or form electrical connections withsuch components. The frame 500 further includes frame elements 538 whichultimately form part of a lead frame but are not needed for the finalframe configuration and are removed during the assembly process asdescribed below. The frame 500 further includes a pair of sensor contactpads 602 located at opposite ends of the chassis 500 for providingmounting pads for the position sensors 600. The mounting pads 602 areconnected to electrical circuitry that provides control signals tocontrol circuitry.

The electrically conductive frame 500 may be formed having asubstantially uniform thickness. According to one example, the frame hasa minimum thickness of about 100 micron. It should be appreciated thatthe thickness and width of the elements of the frame 500 may determinethe structural integrity of the frame 500 and should be selected toallow for reshaping of contact connections as explained herein. Theframe 500 may be formed by employing a photoetch technique, according toone embodiment. Alternately, frame 500 may be formed via other framefabrication techniques employing one or more of stamping, molding,printing or otherwise fabricating the electrically conductive frame 500.The frame 500 may be easily handled during the assembly process.Following formation of the electrically conductive frame 500, one ormore electrical components are assembled to the frame 500. As seen inFIG. 37, electrical components 540, 542, 544 and 546 are shown mountedon top of certain contact pads and electrically connected to the frame500 to form a desired circuit configuration. In the embodiment shown,electrical component 540 may include timing circuitry, such asoscillator crystal, configured to provide a timing signal (e.g., 32kilohertz). Timing circuitry 540 is shown positioned on top of contactpads 502, 504 and 506. Component 542 may include an inductor positionedon top of contact pads 508 and 510. Component 544 may include acapacitor connected across contact pads 512 and 514. The capacitor,inductor, and optional resistor(s) may be configured to provide avoltage boost circuit. Component 546 may include an Application SpecificIntegrated Circuit (ASIC) chip disposed on top of pad 516 and providingelectrical connection to circuit elements leading thereto. The ASIC 546may serve as control circuitry for controlling the activation of theactuator to actuate the valve. The timing circuitry 540, inductor 542,capacitor 544 and ASIC chip 546 may be configured to control activationof the valve actuator by supplying electrical current to the appropriateSMA wire actuator 82 a or 82 b to open and close the valve and therebycontrol the entry of fluid to the fluid consuming cell 20. The positionsensors 600 are mounted on top of the sensor contact pads 602 and senseposition of the moving plate 66. While a specific example of electricalcomponents are shown provided on the frame 500, it should be appreciatedthat other circuit components and circuit arrangements may be employedwithout departing from the teachings of the present invention.

Following assembly of the electrical components 540-546 onto the frame500, the frame 500 is potted in the chassis 550 as shown in FIG. 38. Thechassis 550 includes an electrically non-conductive material thatsubstantially encapsulates circuit elements of the frame 500 and theelectrical components 540-546 assembled thereto. Chassis 550 may includesubstrate materials suitable for use in printed circuit boards.According to one embodiment, the chassis 550 may include an epoxy, suchas EPICLAM™ L9035 (Epic Resins Electronic Products, Palmyra, Wis., USA)or ADTECH™ EL-323-TC-1 epoxy (Cass Polymers, Oklahoma City, Okla., USA).According to one example, the epoxy forming the chassis 550 has acoefficient of thermal expansion of 5.8 parts per million per degree C.(ppm/° C.), and the KOVAR® forming the frame 500 has a coefficient ofthermal expansion of 5 ppm/° C. Thus, the coefficients of thermalexpansion of the frame 500 and chassis 550 are substantially matched.The chassis 550 has low fluid (e.g., air) permeability and expands andcontracts with the frame 500 due to the substantially matched CTEs. Theelectrically non-conductive material of the chassis 550 may be moldedover the frame 500 by employing conventional molds to achieve a desiredconfiguration. In embodiments in which the chassis 550 does not have asufficiently low fluid permeability, the chassis 550 can be coated withanother material having a lower permeability.

In the embodiment shown in FIG. 38, the chassis 550 is formed having agenerally rectangular main body formed around and encapsulating the maincircuit elements of frame 500. Additionally, the chassis 550 includes aninward protruding ledge 552 that extends below contact pads 520 of frame500. The ledge 552 provides an upper surface that abuts the top surfaceof the periphery of moving plate 66 of the valve. Extending from theledge 552 are diagonal ribs 554 and a reduced height body 556 whichencapsulates additional circuit components assembled on the frame 500.The chassis 550 has a shape and size configured to substantiallyencapsulate the circuit elements of the frame 500 and the electricalcomponents 540-546 assembled thereto. It should be appreciated that thechassis 550 may be molded to accommodate the inclusion of an airequalization path such as that shown in FIGS. 31-34 and describedherein.

The chassis 550 has a plurality of crimp connector openings 560 that maybe formed during the molding of the chassis 550 or may be subsequentlyformed by machining or cutting and removing material to form the crimpconnector openings 560 after the molding process. The crimp connectoropenings 560 are adapted to receive the SMA wire crimps 562 such thatthe crimps 562 are press fit into the crimp openings 560 and the SMAwires 82 a and 82 b make electrical contact with contact pads 520. Thecontact pads 520 and the electrical connection formed by the crimps 562and/or SMA wires 82 a and 82 b is described herein according to a fewembodiments.

Referring to FIG. 39, remnant elements of the electrically conductiveframe 500 that are not needed are removed. This includes removal offrame elements 538. Thus, elements 538 provide structural rigidity andallow for handling of the lead frame 500 prior to and during assembly.Elements 538 are subsequently removed prior to completion of the fluidregulating system 50 and its assembly to the battery cell 20.

Referring to FIG. 40, the valve and actuator are shown assembled to thechassis 550. The moving plate 66 of the valve is inserted below theinward extending ledge 552 and the underlying fixed plate 62 isassembled to the bottom surface of chassis 550. Fixed plate 62 may beadhered, fastened or otherwise connected to chassis 550. The lever 84 isconnected to the moving plate 66 and the pivot portion 86 is disposedwithin an opening 586 in the chassis 550 such that the lever 84 is ableto pivot and rotate to move moving plate 66 left and right to open andclose the valve.

SMA wire crimps 562 are press fit within the crimp connector openings560 in chassis 550. In the first embodiment shown, crimps 562 are pressfit and fully inserted to the bottom of respective openings 560 suchthat the SMA wires 82 a and 82 b make electrical contact with contactpads 520. As seen in greater detail in FIGS. 41 and 42, the crimp 562 ispress fit fully to the bottom of the opening 560 such that sufficientelectrical contact exists between the SMA wire 82 a and contact pad 520.In this embodiment, crimp 562 is pressed onto the circuit path formingcontact pad 522, as seen in FIG. 42, and is held in place due to theinterference fit between the walls of the opening 560 and the crimp 562.The crimp 562 has a size and shape (e.g., cylinder) that substantiallymatches the size and shape of opening 560. The SMA wires 82 a and 82 bare also shown in electrical contact with respective contact pads 520such that current supplied via contact pads 520 may pass through one ofSMA wires 82 a and 82 b. It should be appreciated that an adhesive, suchas a conductive adhesive may be applied to hold the crimps 562 in placerelative to openings 560 and maintain electrical contact between the SMAwires 82 a and 82 b and the respective contact pads 520. An electricallynonconductive plug (not shown) could further be inserted on top ofcrimps 562 to isolate the crimps 526 from the overlying battery cell 20.

Referring to FIGS. 43 and 44, an alternate electrical connection betweencrimp 562 and contact pad 520 is shown therein. In this embodiment, thecontact pad 520 is folded inward within crimp connector opening 560 intoa generally W-shape as seen in FIG. 43. The bent W-shape of contact pad520 is generally resilient such it provides a spring-likecharacteristic. The crimp 562 is press fit within the walls of opening560 and forced downward so as to engage and compress against theresilient contact pad 520. It should be appreciated that by folding thecontact pad 520, the contact pad has a resilience that provides aspring-like bias to maintain adequate electrical contact between thecontact pad 520 and the crimp 562 and/or SMA wire connected thereto. Asseen in FIG. 44, the crimp 562 is fully inserted into the crimp opening580 and remains in biased contact with contact pad 520.

Referring to FIGS. 45 and 46, the contact pad 520 is shown folded inwardwithin crimp connector opening 560 in another configuration according toa further embodiment. In this configuration, contact pad 520 providesone or more electrically conductive elements that are resilient andextend upward from the bottom of the crimp connector opening 560. Thecrimp 562 is press fit within the crimp connector opening 560 so as tocompress against the contact pad 520 as seen in FIG. 46. It should beappreciated that other size and shaped contacts may be employed tocontact the crimp 562 and/or the SMA wires 82 a and 82 b.

Following assembly of the actuator and valve to the chassis 550 andframe 500, the fluid consuming cell 20 is assembled to the top surfaceof the chassis 550 as seen in FIG. 47. It should be appreciated that thefluid consuming cell 20 may be adhered, fastened or otherwise connectedto the chassis 520.

With the fluid consuming cell 20 attached to the chassis 550, thebattery contacts are bent upwards and into contact with appropriateterminals of the fluid consuming cell 20. In the embodiment shown inFIG. 48, battery contacts 530, 534 a and 534 b are bent upwards and intocontact with the side wall of the can 34 which forms the positiveterminal. It should further be appreciated that the battery contact 532(not seen) likewise makes contact with the side wall of the can 34forming the positive terminal. The remaining battery contacts 536 a and536 b are bent upwards and into contact with the cover 36 forming thenegative terminal of the fluid consuming cell 20. The bending of thebattery contacts may be achieved by placing the battery 10 in a die toreshape the conductive elements. An underlying electrically insulatingtape 580 is applied below battery contacts 536 a and 536 b on the sidewall of the can 34 so as to electrically insulate contacts 536 a and 536b from the positive battery terminal. The battery contacts 536 a and 536b extend further beyond insulating tape 580 onto and in contact with thecover 36 forming the negative battery terminal. An overlyingelectrically insulating tape 582 is then applied over the batterycontacts 536 a and 536 b as seen in FIG. 49.

Accordingly, the fluid regulating system 50 and resulting battery 10advantageously employs a chassis 550 having an integrally formedelectrically conductive frame 500 formed therein, and electricalcomponents that are substantially encapsulated within the chassis 550.The resulting assembly of the electrically conductive frame 500 in thechassis 550 is easy to assemble and results in a protective structureover the circuit elements and components that is not susceptible toleakage of fluid through the chassis 550.

The chassis 550 may be molded over at least part of the position sensors600 and connecting circuitry such that the position sensors 600 areconsidered embedded or at least partially embedded in the chassis,according to one embodiment. It should be appreciated that part of theposition sensors 600 and connecting circuitry may be embedded while partof each position sensor may extend from the chassis 550 to a locationthat may sense the position of the moving plate 66 of the valve so as todetermine at least whether the valve is in the open or closed position.

Referring to FIG. 50, the position sensors 600 are further illustratedin relation to the moving plate 66. In the open valve position, movingplate 66 may contact one of the position sensors 600. At the otherextreme position, in the closed position of the valve, moving plate 66may contact the other position sensor 600. By providing contact betweenthe electrically conductive moving plate 66 and one of the positionsensors 600, a closed contact connection may indicate the open or closedposition of the moving plate 66. Alternately, it should be appreciatedthat non-contact sensors 600 may be employed to sense when the movingplate 66 is in either of the open and closed positions. For example,capacitive or laser sensors may be used to sense distance from thesensor 600 to the moving plate 66. Further, one or two position sensors600 may be employed to sense position of the moving plate 66 atintermediate locations between the open and closed positions. It shouldbe appreciated that one or more position sensors 600 may be employed ina variety of valve configurations to sense the open and closed positionsof the valve for regulating fluid to a fluid consuming battery,including the various embodiments of the fluid regulating systemdisclosed herein.

Referring to FIG. 51, valve control circuitry 610 is illustrated,according to one embodiment. According to this embodiment, the valvecontrol circuitry 610 employs a controller 620. According to oneembodiment, the controller 620 may include an Application SpecificIntegrated Circuit (ASIC) configured with logic, such as software, whichexecutes a state logic routine 700. The ASIC may be configured on a chipsuch as component 546 shown in FIG. 37. According to another embodiment,the controller 620 may include a microcontroller that has amicroprocessor and may include memory such as random access memory (RAM)and read-only memory (ROM). The microcontroller 620 executes the statelogic 700 as described herein for processing sensed inputs and providingcontrol output signals to control the valve actuation. The controlcircuitry 610 may be included with or used in place of component 546 inFIG. 37 or control circuitry 90 shown in FIGS. 4, 6-8 and 11.

The valve control circuitry 610 is also shown includinganalog-to-digital converter (ADC) circuitry 654 which receives variousinputs and converts the analog inputs to digital signals which are inputto the controller 620. Timing circuitry 638 provides a timing signal tothe controller 620. Additionally, a pulse timer 1 in block 626 and apulse timer 2 in block 628 are provided to provide inputs to thecontroller 620 for defining time periods for opening and closing thevalve, respectively.

The valve control circuitry 610 receives various inputs including sensedvoltages +VE and −VE which are indicative of the sensed battery voltageacross the positive and negative terminals of the battery at inputterminals 612 and 614. The sensed voltages from inputs 612 and 614 areinput to a reverse polarity protection circuit 616 which protectsagainst reverse polarity connection with the battery. The sensedvoltages +VE and −VE are also input to a voltage sensor and windowcompare circuit 618. The voltage sensor and window compare circuit 618senses the differential voltage and compares the battery voltage tovoltage threshold values that define a window of operation. According toone embodiment, a first low voltage of 1.10 volts is used as the lowthreshold voltage to decide whether to open the valve and supply fluidto the battery when the sensed voltage drops below the first lowthreshold of 1.10 volts. According to this embodiment, a second highvoltage of 1.275 volts is employed as the high threshold voltage todecide whether to close the valve when the sensed voltage exceeds thesecond high threshold of 1.275 volts. An output of the voltage sensorand window compare circuit 618 is provided as an input to the controller620. Additionally, a 0.9 volt to 3.0 volt charge pump 636 is providedfor providing a stepped up voltage that may be used for operation of thecircuitry.

The valve control circuitry 610 also receives various sensor inputswhich are converted from analog to digital signals by way of theanalog-to-digital converter 654. Included are signal inputs from one ormore position sensors 600 for sensing position of the moving plate ofthe valve. Additionally, a humidity sensor 632 senses humidity of thevalve and provides an input to control circuitry 610. Further, atemperature sensor 634 senses temperature of the valve and provides thesensed temperature signal to the control circuitry 610. It should beappreciated that the humidity sensor 632 and the temperature sensor 634essentially sense an operating condition of the fluid regulating system.By sensing an operating condition of the fluid regulating system, aminimum required time T_(MIN) used for maintaining the valve in the openposition may be determined based on the sensed operating condition. Theminimum required time T_(MIN) may be dynamically adjusted periodicallybased on the sensed operating condition by selecting the time T_(MIN)from a lookup table. Further, it should be appreciated that the positionsensor may provide a position signal which may be indicative of a wearparameter of the valve such that it also provides a sensed operatingcondition of the fluid regulating system. As used herein, a wearparameter means a property, such as a physical or electrical property,of a valve component that can change during the useful life of the valvein such a way as to be useful, such as in estimating a point in thevalve's expected lifetime or an indication of the valve's impendingfailure. For example, the time or energy required for a valve to movefrom one position to another, as indicated by a pair of positionsensors, may gradually increase over time and/or become excessiveshortly before the valve will no longer operate acceptably. Such changesmay be due to factors such as physical wear caused by friction, fatiguedue repeated motions, improper operation or failure due to dirt orbreaks, and so on.

The valve control circuitry 610 provides output signals to drivercircuitry 642. The driver circuitry 642 may include drive transistors,according to one embodiment, that generate drive signals at outputs 644and 646 to drive the actuators to open and close the valve.

Referring to FIG. 52, the state logic routine 700 executed by thecontroller is illustrated according to one embodiment. The logic routine700 includes a power on state in block 702 in which a device to bepowered is energized. In the power on state 702, a fluid consuming cell,such as a zinc-air cell, is connected to the valve switching controlcircuitry and a power on reset is activated. Prior to being powered on,the valve is in the valve closed state as shown in block 704. In thevalve closed state 704, the SMA drivers are disabled and the voltagesensor is enabled. The valve will remain in the valve closed state 704until either the battery cell voltage drops below the lower firstthreshold of 1.10 volts or if the rate of change of battery electricaloutput, such as rate of change of voltage (dv/dt), exceeds a rate ofchange threshold, such as 400 millivolts/second as shown by event 706.Upon event 706 occurring, the valve begins to transition to an openvalve state during which the valve begins to open by applying power tothe appropriate SMA actuator. In the open valve state 708, the voltagesensor is disabled, and the SMA driver for actuating the valve to theopen position is enabled to activate the actuator. The valve, onceactuated, will then transition to a valve open state 712 following aperiod of time as determined by pulse timer 1. According to one example,the pulse timer period is about 0.5 seconds. This provides sufficienttime for the SMA driver to drive the valve to the full open position. Inthe valve open state 712, the SMA driver for opening the valve isdisabled, and the status of the position sensor(s) is checked. Once inthe valve open state 12, routine 700 waits for a time periodt_valve-open debounce to prevent the occurrence of false triggering instep 714. Time period t_valve-open debounce may be a predetermined timeperiod, such as 50 ms in one example, sufficient to realize a steadyvoltage output. Routine 700 then proceeds to valve open state 716. Atvalve open state 716, the voltage sensor is enabled and the minimum timeperiod T_(MIN) required for keeping the valve open is calculated.

While in the valve open state 716, routine 700 checks in step 718 forwhether the minimum required time T_(MIN) has expired and, if not,maintains the valve in the valve open state 716. It should beappreciated that the minimum time period T_(MIN) maintains the valve inthe open position, such that the valve is not repeatedly opened andclosed. Additionally, the minimum required time T_(MIN) is used tomaintain the valve in the open position in a manner that minimizes theuse of energy by the valve actuator and a corresponding battery capacityloss to otherwise open the valve earlier by requiring that the valve bemaintained in an open position for the minimum time period T_(MIN). Thevalve is thereby restricted from actuating at a greater frequency sothat battery capacity is not wasted. The minimum time period T_(MIN) canbe calculated based on the battery capacity required to open and closethe valve and the battery capacity lost while the valve is open. Theminimum time period T_(MIN) may initially be computed by calculating afirst battery capacity loss required to close the valve, calculating asecond battery capacity loss required to open the valve, calculating abattery capacity loss rate by leaving the valve in the open position,and calculating the minimum required time based on a comparison of thecalculated first and second battery capacity losses and the calculatedbattery capacity loss rate. Variations in the minimum required timeT_(MIN) may then be stored in memory based on one or more operatingconditions, such as temperature and used to maintain the valve in theopen position upon actuation.

According to one embodiment, the minimum required time period T_(MIN) isdetermined based on a sensed operating condition. More specifically, theminimum required time period T_(MIN) is dynamically adjusted based onthe sensed operating condition. The sensed operating condition mayinclude sensed temperature, according to one embodiment. According toanother embodiment, the sensed operating condition may comprise humiditysensed with a humidity sensor. According to a further embodiment, thesensed operating condition may comprise a wear parameter. The sensedwear parameter may be determined based on a known state of the valve andthe position sensor sensing the valve in open and closed positions.

The valve remains in the valve open state 716 until both events in step720 of the cell voltage exceeding the upper second voltage limit of1.275 volts and the minimum time period T_(MIN) has expired. If the cellvoltage exceeds the upper second voltage threshold of 1.275 volts andthe minimum time period T_(MIN) has expired, the valve transitions tothe close valve state 722 during which the valve is actuated towards theclosed position. In the close valve state 722, the voltage sensor isdisabled and the SMA driver for closing the valve is enabled. The valvethen transitions to the valve closed state 726 after waiting for aperiod of time set by pulsed timer 2, such as 0.5 seconds in oneexample, in step 724. In the valve closed state 726, the voltage sensoris enabled and the status of the position sensor is checked. The routine700 then proceeds to further transition to the valve closed state 704after a time period t_valve-closed debounce in step 728 to prevent theoccurrence of false triggering. The time period t_valve-closed may be apredetermined time, such as 50 ms, sufficient to realize a steady stateoutput voltage. In the valve closed state 704, the SMA drivers aredisabled and the voltage sensor is enabled. It should be appreciatedthat the routine 700 may then be repeated amongst the various states.

The fluid regulating system advantageously controls the fluid suppliedto the fluid consuming battery by monitoring the voltage of the batteryand controlling the supply of fluid to the fluid consuming battery byopening the valve when the monitored voltage drops below a first lowerthreshold voltage of 1.10 volts per cell and by closing the valve whenthe voltage rises above a second upper voltage of 1.275 volts per cell.Additionally, the fluid regulating system and method of the presentinvention further monitor a rate of change in battery voltage withrespect to time. Specifically, the rate of change of voltage dv/dt ofthe battery is monitored and compared to a voltage rate of changethreshold, such as 400 millivolts/second/cell, and the valve is openedwhen the monitored rate of change in voltage exceeds the rate of changethreshold. It should be appreciated that while the rate of change ofbattery electrical output is shown and described herein as a rate ofchange of voltage, it should be appreciated that a variety of energymeasurements can be used, such as open circuit voltage, closed circuitvoltage, current, power and combinations thereof, according to otherembodiments. According to another embodiment, the battery electricaloutput monitored may include battery current detected by a currentdetector, and the rate of change in battery current is compared to acurrent rate of change threshold. According to one embodiment, the rateof change in voltage is monitored when the valve is in the closedposition, and the rate of change in voltage is the rate of decrease involtage. It should be appreciated that by opening the valve when themonitored rate of change of voltage exceeds the voltage rate of changethreshold, the fluid regulating system and method of the presentinvention advantageously opens the valve more quickly so as to preventdisruption in service of the device being powered by the battery.Further, the rate of change threshold may be adjusted based on a sensedoperating condition. According to one embodiment, the sensed operatingcondition for adjusting the rate of change threshold is at least onemember of the group consisting of a temperature, humidity and a wearparameter. According to another embodiment, the sensed operatingcondition may include any one or any combination of temperature,humidity and wear parameters.

The minimum required time period T_(MIN) for maintaining the valve inthe open position is dynamically adjusted based on a sensed operatingcondition. According to one embodiment, the sensed operating conditionis sensed temperature sensed by the temperature sensor. Referring toFIG. 23, a lookup table provides a plurality of temperatures andcorresponding minimum time periods T_(MIN) that may be selected from toadjust the minimum required time, according to one example. As thesensed temperature varies, the minimum required time T_(MIN) isdynamically adjusted as a function of the sensed temperature. Theminimum required time T_(MIN) may be determined by interpolation orextrapolation of the temperature data and may be determined based on anequation. It should be appreciated that a similar lookup table may beemployed based on other sensed operating conditions, such as humidityand wear parameters, and that a combination of multiple sensed operatingconditions may be employed to adjust the minimum required time T_(MIN).

Although the present invention has been described above with respect toa fluid regulating system supplying fluid to single batteries having asingle cell, aspects of the present invention may apply to batterieshaving multiple cells, and battery packs having multiple batteries. Forexample, the fluid regulating system may be completely or partiallydisposed in a housing of a battery pack so as to selectively open andclose a valve that allows air or another fluid to pass into the batterypack housing. In this case, separate fluid regulating systems would notbe needed for each battery. Further, the fluid regulating system couldbe powered from any one or group of the batteries or all of thebatteries within the battery pack or from another battery outside thebattery pack.

The fluid regulating system may also be disposed completely or partiallywithin a device that is powered by the battery, batteries, or batterypack or otherwise provided separate from the battery, batteries, orbattery pack. For example, the valve could be a pre-packaged module thatserves a variety of multi-cell pack sizes. So there may be advantages topackaging the valve, valve power supply and controls separately from thefluid consuming cells.

The combination of a fluid consuming battery and a fluid regulatingsystem can include a module containing all or a portion of the fluidregulating system into which one or more replaceable fluid consumingbatteries are inserted. This allows reuse of at least part of the fluidregulating system, thereby reducing the cost per battery to the user.The module can include one or more fluid inlets and can also includeinternal channels, plenums or other internal spaces that provide apassageway for fluid to reach the battery. The module and battery can beheld together in any suitable manner, including the use of electricalcontacts that are part of the module that cooperate with thecorresponding electrical contacts that are part of the battery toprevent inadvertent separation of the module and battery. For example,the electrical contacts on the module can be in the form of projectingblades that snap into slots in the battery case that contain the batteryelectrical contacts. The blades can be held in the slots by any suitablemeans, such as by interference fit, one or more springs, a mechanicallocking mechanism and various combinations thereof. The module andbattery dimensions, shapes and electrical contacts can be configured toallow mating of the module and battery in only the proper orientationsin order to assure proper electrical contact and prevent batteryreversal. The module, the battery or both can have external contactterminals for making proper electrical contact with a device in whichthe combined battery and module are installed. In some embodiments thebattery can be replaced without removing the module from the device.

While the invention has been described in detail herein in accordancewith certain preferred embodiments thereof, many modifications andchanges therein may be affected by those skilled in the art withoutdeparting from the spirit of the invention. Accordingly, it is ourintent to be limited only by the scope of the appending claims and notby way of the details and instrumentalities describing the embodimentsshown herein.

1. A method of controlling fluid supplied to a fluid consuming battery,said method comprising the steps of: providing a fluid regulating systemthat comprises a valve for adjusting a rate of passage of fluid into afluid consuming electrode of a battery and an actuator for operating thevalve; sensing an operating condition of the fluid regulating system;determining a minimum required time for maintaining the valve in an openposition based on calculated battery capacity losses required to closeand open the valve, a calculated battery capacity loss rate for leavingthe valve in the open position and the sensed operating condition;controlling actuation of the valve to open the valve when greaterbattery electrical output is required; maintaining the valve in the openposition for the minimum required time; and controlling actuation of thevalve to close the valve when lesser battery electrical output isrequired.
 2. The method as defined in claim 1 further comprising thestep of periodically adjusting the minimum required time based on thesensed operating condition.
 3. The method as defined in claim 1, whereinthe minimum required time is computed based on the following steps:calculating a first battery capacity loss required to close the valve;calculating a second battery capacity loss required to open the valve;calculating a battery capacity loss rate by leaving the valve in theopen position; and calculating the minimum required time further basedon a comparison of the calculated first and second battery capacitylosses and the calculated battery capacity loss rate.
 4. The method asdefined in claim 1, wherein the step of determining the minimum requiredtime comprises selecting the minimum required time from a lookup table.5. The method as defined in claim 1, wherein the operating conditioncomprises a sensed temperature.
 6. The method as defined in claim 1,wherein the operating condition comprises a wear parameter.
 7. Themethod as defined in claim 1, wherein the operating condition comprisesa sensed humidity.
 8. The method as defined in claim 1, wherein thefluid consuming electrode comprises an air electrode.
 9. The method asdefined in claim 1, wherein the step of controlling actuation of thevalve to open the valve when greater battery electrical output isrequired comprises controlling actuation of the valve to open the valvewhen a battery voltage falls below a low voltage threshold, and the stepof controlling actuation of the valve to close the valve when lesserbattery electrical output is required comprises controlling actuation ofthe valve to close the valve when the battery voltage exceeds an uppervoltage threshold.
 10. The method as defined in claim 1 furthercomprising the steps of monitoring a rate of change of battery voltageand controlling the valve to open the valve based on the monitored rateof change of battery voltage.
 11. The method as defined in claim 1further comprising the step of sensing position of the valve.
 12. Themethod as defined in claim 1, wherein the valve comprises a moveableplate and the valve is opened and closed by moving the moveable plate.13. The method as defined in claim 1, wherein the actuator is controlledto open the valve when greater battery voltage is required and to closethe valve when lesser battery voltage is required.
 14. The method asdefined in claim 1, wherein at least a portion of the fluid regulatingsystem is disposed in a device powered by the fluid consuming battery.15. The method as defined in claim 1, wherein the sensed operatingcondition consists of one or more of a temperature, a wear parameter anda humidity.